Spacecraft proximity maneuvering, rendezvous, and docking procedures arise in most space missions, including those with commercial satellites, cargo transfer spacecraft, lunar mission spacecraft and various repair and service spacecrafts. It is well known that conventional spacecraft docking mechanisms include precise control of inertial propulsion systems, such as thrusters, to position an active craft (chaser) in motion relative to a passive craft (target) for docking. Inertial propulsion systems tend to be difficult to control and present a risk of misalignment and possible collision and damage to the spacecraft. Two current approaches to resolve this include manual docking and autonomous docking.
Typical manual docking systems include a video sensor or camera, which generates a visual output for use by a pilot to control docking and maneuvering. A difficulty encountered with manual systems is that it is often impractical or impossible for a pilot to manually maneuver a spacecraft for docking or berthing. For example, some space missions are tenuous and may endanger the pilot, while other space missions include unmanned spacecraft.
Docking operations between autonomous spacecraft require precise knowledge of relative vehicle position and attitudes. If the docking target vehicle is not equipped to generate attitude data for the docking chaser vehicle, the chaser must include sensors or computation-intensive data processing to determine relative position and attitude to the target. Docking based on visible light image data requires advantageous lighting, and it is difficult for cameras to provide adequate image detail for attitude and range estimation.
Further, docking with a disabled or passive vehicle is a design requirement for some missions. Therefore, the design solution should not require power or control from the docking target vehicle.
The disadvantages associated with current docking systems have made it apparent that a new docking system is needed. The new docking mechanism should be an autonomous rendezvous and docking system and should also provide an accurate docking alignment while requiring minimal input or response from the target spacecraft.